This concerns politics.
Let's take the stance for the sake of argument that after a certain age, a human being is physiologically incapable (that is, it is physically, logically impossible) of changing their mind.
Let's further take the stance that killing human beings in order to extinguish an antisocial faith is verboten. Whatever we think about moral offenses, we agree that killing in order to extinguish the motive faith that animates such antisocial behavior (which defines the faith as antisocial; its fruit), is off the table.
Given the above, how do we deal with people who only live because we have mercifully granted them their lives, because in another time, they would be condemned and killed, by us, humanity, in the hopes of extinguishing forever the motivating faith residing in a person above a certain age who commits antisocial crimes, even regularly.
The least we can do is not kill them, given what they had to deal with.
What should we the Church do?